Method and apparatus for controlling scell state

ABSTRACT

Provided is a method and an apparatus for changing or controlling a state of a secondary cell in carrier aggregation. The method includes receiving secondary cell (SCell) state indication information indicating a state for a SCell from a base station through an RRC message or an MAC control element, causing a state of the SCell to transition into a dormant state when the SCell state indication information indicates the dormant state, and transmitting channel state information reporting for the SCell in the dormant state according to an dormant state CQI report period parameter set separately from an activation state CQI report period parameter.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Applications No.10-2017-0178384, filed on Dec. 22, 2017, No. 10-2018-0027301, filed onMar. 8, 2018, & No. 10-2018-0124177, filed on Oct. 18, 2018 which arehereby incorporated by reference for all purposes as if fully set forthherein.

BACKGROUND 1. Technical Field

The present disclosure relates to controlling and changing a state of asecondary cell.

2. Description of the Related Art

Studies on next generation mobile communication technologies have beenin progress for satisfying demands for processing a large amount of dataat a high-speed. For example, mobile communication systems have beenemployed technologies related to the 3rd generation partnership project(3GPP), such as Long Term Evolution (LTE), LTE-Advanced, 5G, fortransmitting and receiving a large amount of various types of data, suchas video data, radio data, at a high speed.

As another method for satisfying the demands, carrier aggregation hasbeen introduced. Such carrier aggregation enables a user device (e.g.,user equipment) and a base station to transmit and receive data byaggregating a plurality of carriers.

However, in order to transmit and receive data through the carrieraggregation, a user equipment and a base station are required to performa complex procedure, such as, operations of the user equipment formeasuring the quality of a target carrier and reporting the measuredquality to a base station and operations of the base station forselecting one or more carriers and determining the carrier aggregation.

In addition, when a secondary cell configured through the carrieraggregation triggers state transition from a deactivation state into anactivation state, a related user equipment and base station perform acomplex procedure and causes a certain time delay intransmitting/receiving data using the secondary cell after the statetransition has been performed into the activation state.

Such a time delay degrades service satisfaction from a user and anetwork perspective.

SUMMARY

To address such issues, the present disclosure is to provide a methodand an apparatus for enabling a secondary cell to quickly perform statetransition through a dormant state.

In addition, the present disclosure is to provide specific operationsand procedures for controlling states for a secondary cell.

In accordance with an aspect of the present disclosure, a method of auser equipment is provided for controlling states of a secondary cell.The method includes receiving secondary cell (SCell) state indicationinformation indicating a state for the SCell from a base station throughan radio remote control (RRC) message or a medium access control (MAC)control element, causing a state of the SCell to transition into adormant state when the SCell state indication information indicates thedormant state, and transmitting channel state information reporting forthe SCell in the dormant state according to an dormant state CQI reportperiod parameter set separately from an activation state CQI reportperiod parameter.

In accordance with another aspect of the present disclosure, a method ofa base station is provided for controlling states of a secondary cell ofa user equipment. The method includes transmitting secondary cell(SCell) state indication information indicating a state for the SCell tothe user equipment through an RRC message or a MAC control element, andwhen the SCell enters a dormant state according to the SCell stateindication information, receiving channel state information reportingfor the SCell in the dormant state according to an dormant state CQIreport period parameter set separately from an activation state CQIreport period parameter.

In accordance with another aspect of the present disclosure, a userequipment is provided for controlling states of a secondary cell. Theuser equipment includes a receiver configured to receive secondary cell(SCell) state indication information indicating a state for the SCellfrom a base station through a RRC message or a MAC control element, acontroller configured to cause a state of the SCell to transition into adormant state when the SCell state indication information indicates thedormant state, and a transmitter configured to transmit channel stateinformation reporting for the SCell in the dormant state according to andormant state CQI report period parameter set separately from anactivation state CQI report period parameter.

In accordance with another aspect of the present disclosure, a basestation is provided for controlling states of a secondary cell of a userequipment. The base station includes a transmitter configured totransmit secondary cell (SCell) state indication information indicatinga state for the SCell to the user equipment through an RRC message or aMAC control element, and when the SCell enters a dormant state accordingto the SCell state indication information, a receiver configured toreceive channel state information reporting for the SCell in the dormantstate according to an dormant state CQI report period parameter setseparately from an activation state CQI report period parameter.

In accordance with the present disclosure, it is possible to performoperations rapidly even when a state is transitioned into an activationstate by defining a dormant state of a secondary cell configuringcarrier aggregation.

In accordance with the present disclosure, it is also possible toeliminate the ambiguity of operations by defining methods and signalsfor changing a Scell′ states including a dormant state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating operations of a user equipmentaccording to at least one embodiment of the present disclosure.

FIG. 2 is a diagram illustrating an RRC message including SCell stateindication information according to at least one embodiment of thepresent disclosure.

FIG. 3 is a flowchart illustrating operations for controlling a state ofa SCell through an RRC message according to at least one embodiment ofthe present disclosure.

FIG. 4 is a diagram illustrating a format of a MAC control element (MACCE) according to one embodiment of the present disclosure.

FIG. 5 is a diagram illustrating a format of a MAC CE according toanother embodiment of the present disclosure.

FIG. 6 is a diagram for describing a procedure of changing a state of aSCell according to a MAC CE including SCell state indication informationaccording to at least one embodiment of the present disclosure.

FIG. 7 is a diagram illustrating examples of logical channel identifier(LCID) values according to at least one embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrating operations for determining a state of aSCell in the case of receiving all MAC CEs different from each otheraccording to at least one embodiment of the present disclosure.

FIG. 9 is a flowchart illustrating operations of a base stationaccording to at least one embodiment of the present disclosure.

FIG. 10 is a diagram illustrating a list of logical channel identifier(LCID) values for a DL-SCH according to an embodiment of the presentdisclosure.

FIG. 11 is a diagram illustrating a format of a MAC CE according toanother embodiment of the present disclosure.

FIG. 12 is a diagram illustrating a format of a MAC PDU including a MACheader and a MAC payload according to at least one embodiment of thepresent disclosure.

FIG. 13 is a diagram illustrating a format of a MAC subheader.

FIG. 14 is a diagram illustrating timing for receiving each ofactivation state indication information, dormant state indicationinformation, and deactivation state indication information for a SCellaccording to at least one embodiment of the present disclosure.

FIG. 15 is a block diagram illustrating a user equipment according to atleast one embodiment of the present disclosure.

FIG. 16 is a block diagram illustrating a base station according to atleast one embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. In adding referencenumerals to elements in each drawing, the same elements will bedesignated by the same reference numerals, if possible, although theyare shown in different drawings. Further, in the following descriptionof the present disclosure, a detailed description of known functions andconfigurations incorporated herein will be omitted when it is determinedthat the description may make the subject matter of the presentdisclosure rather unclear.

In the present disclosure, a wireless communication system refers to asystem for providing various communication services such as a voicecommunication service, a packet data service, etc. The wirelesscommunication system includes user equipment (UE) and a base station(BS).

The UE is defined as a generic term including devices used in wirelesscommunication. For example, the UE may be referred to as a UE supportingwideband code division multiple access (WCDMA), long term evolution(LTE), high speed packet access (HSPA), international mobiletelecommunications (IMT)-2020 (5G or new radio), and the like, a mobilestation (MS) supporting the global system for mobile communication(GSM), a user terminal (UT), a subscriber station (SS), a wirelessdevice, or the like. However, the embodiments of the present disclosureare not limited thereto.

The BS or a cell generally refers to a station communicating with theUE. The BS or cell is defined as a generic term including all of variouscoverage areas. For example, the BS or the cell may be referred to as aNode-B, an evolved Node-B (eNB), a gNode-B (gNB), a low power node(LPN), a sector, a site, various types of antennas, a base transceiversystem (BTS), an access point, a point (e.g., a transmitting point, areceiving point, or a transceiving point), a relay node, a megacell, amacrocell, a microcell, a picocell, a femtocell, a remote radio head(RRH), a radio unit (RU), and a small cell. However, embodiments of thepresent disclosure are not limited thereto.

Since each of the various cells described above is controlled by a BS,the BS may be classified into two categories. 1) The BS may be referredto an apparatus that provides a megacell, a macrocell, a microcell, apicocell, a femtocell, and a small cell, in association with a radioarea, or 2) the BS may be referred to a radio area itself. In case of1), the BS may be referred to apparatuses providing a correspondingwireless service area by being controlled by the same entity orapparatuses providing a corresponding wireless service area byinteracting and cooperating together. According to a method ofestablishing (e.g., providing, forming, configuring) a radio area (e.g.,wireless service area), an example of the BS may be a point, atransmission/reception point, a transmission point, a reception point,or the like. In case of 2), the BS may be a radio area itself forreceiving or transmitting a signal from a UE perspective or aneighboring BS perspective.

In the present disclosure, the cell may refer to a coverage of a signaltransmitted from a transmission/reception point, a component carrierhaving the coverage of a signal transmitted from a transmission point ora transmission/reception point, or a transmission/reception pointitself.

The UE and the BS are two entities for performing transmission/receptionused to embody the technology and technical spirit described in thepresent disclosure. The UE and the BS are defined as a generic term andnot limited to specific terms or words.

The uplink (UL) refers to a scheme for a UE to transmit data to orreceive data from a BS, and the downlink (DL) refers to a scheme for aBS to transmit data to or receive data from a UE.

UL transmission and DL transmission may be performed by utilizing i) atime division duplex (TDD) technique performing transmission throughdifferent time slots, ii) a frequency division duplex (FDD) techniqueperforming transmission through different frequencies, or iii) a hybridtechnique of the frequency division duplex (FDD) and the time divisionduplex (TDD).

Further, a related standard of the wireless communication system definesto configure the UL and the DL based on a single carrier or a pair ofcarriers.

The UL and the DL transmit control information through one or morecontrol channels, such as a physical DL control channel (PDCCH), aphysical UL control channel (PUCCH), and the like. Further, the UL andthe DL transmit data through one or more data channels, such as aphysical DL shared channel (PDSCH), a physical UL shared channel(PUSCH), and the like.

The DL may denote communication or a communication path from multipletransmission/reception points to a UE, or the UL may denotecommunication or a communication path from the UE to the multipletransmission/reception points. In the DL, a transmitter may be a part ofmultiple transmission/reception points, and a receiver may be a part ofthe UE. In the UL, a transmitter may be a part of the UE and a receivermay be a part of multiple transmission/reception points.

Hereinafter, transmission and reception of a signal through a channelsuch as the PUCCH, the PUSCH, the PDCCH, or the PDSCH, may be describedas the transmission and reception of the channel, such as the PUCCH, thePUSCH, the PDCCH, or the PDSCH.

Meanwhile, higher layer signaling described below includes radioresource control (RRC) signaling that transmits RRC informationcontaining an RRC parameter.

The BS performs DL transmission to USs. The BS may transmit a physicalDL control channel for transmitting □) DL control information, such asscheduling required to receive a DL data channel that is a primaryphysical channel for unicast transmission, and □) scheduling approvalinformation for transmission through an UL data channel. Hereinafter,transmission/reception of a signal through each channel will bedescribed as transmission/reception of the corresponding channel.

Any of multiple access techniques may be applied to the wirelesscommunication system, and therefore no limitation is imposed on them.For example, such multiple access techniques may include time divisionmultiple access (TDMA), frequency division multiple access (FDMA), CDMA,orthogonal frequency division multiple access (OFDMA), non-orthogonalmultiple access (NOMA), OFDM-TDMA, OFDM-FDMA, OFDM-CDMA, or the like.The NOMA includes sparse code multiple access (SCMA), low cost spreading(LDS), and the like.

At least one embodiment of the present disclosure may be apply toresource allocation in i) asynchronous wireless communication evolvinginto LTE/LTE-advanced and IMT-2020 from GSM, WCDMA, and HSPA, and ii)synchronous wireless communication evolving into CDMA, CDMA-2000, andUMB.

In the present disclosure, a machine type communication (MTC) device mayrefer to a device supporting low cost (or low complexity), a devicesupporting coverage enhancement, or the like. As another example, theMTC device of the present disclosure may refer to a device defined as apredetermined category for supporting low cost (or low complexity)and/or coverage enhancement.

In other words, the MTC device may refer to a low cost (or lowcomplexity) UE category/type newly defined in 3GPP Release-13 andperforming LTE-based MTC-related operations. As another example, the MTCdevice may refer to a UE category/type defined in or before 3GPPRelease-12, which supports enhanced coverage in comparison with thetypical LTE coverage or supports low power consumption, or may refer toa low cost (or low complexity) UE category/type newly defined inRelease-13. The MTC device may refer to a further enhanced MTC devicedefined in Release-14.

In the present disclosure, a narrowband Internet of Things (NB-IoT)device refers to a device supporting radio access for cellular IoT.NB-IoT technology aims at improved indoor coverage, support forlarge-scale low-speed devices, low latency sensitivity, very low devicecosts, low power consumption, and optimized network architecture.

An enhanced mobile broadband (eMBB), massive machine-type communication(mMTC), and ultra-reliable and low latency communication (URLLC) areproposed as representative usage scenarios for NR.

A frequency, a frame, a subframe, a resource, a resource block (RB), aregion, a band, a sub-band, a control channel, a data channel, asynchronization signal, various reference signals, various signals, andvarious messages associated with NR of the present disclosure may beinterpreted as being used in the past or present or as various meaningsto be used in the future.

Hereinafter, a method and an apparatus for controlling carrieraggregation and a state of a secondary cell in accordance withembodiments of the present disclosure will be described in detail.

In the present disclosure, a secondary cell denotes a cell providing anadditional radio resource other than a primary cell (PCell) serving as areference for RRC connection when a UE configures carrier aggregation.The secondary cell may be described as SCell, but the term is notlimited thereto. In addition, in the present disclosure, description orembodiments related to state changes of the SCell apply to a normal cellproviding an additional radio resource, and may not apply to the PSCell,or a special cell.

In the present disclosure, an activation state denotes a state capableof transmitting/receiving data by performing operations of a normalSCell. A deactivation state denotes a state in which a SCell isconfigured on a UE, but a transmission or reception operation, or thelike is not performed for the SCell. A dormant state is a state newlydefined in accordance with at least one embodiment. The dormant statedenotes a state in which at least one operation in the activation stateand at least one operation in the deactivation state are mixed. Thedormant state may be replaced by an arbitrary term, such as a fastactivation state, mid activation state, low power activation state, highpower deactivation state, new SCell state, mid power SCell state, midstate, mid activated state, semi activated state, semi deactivatedstate, or the like. Terms on states described above are just examples,and not limited thereto.

In the present disclosure, channel state information reporting includesinformation on channels measured, estimated or calculated by a UE and isdescribed as CSI reporting, CQI reporting, or the like. This is forconvenience of description. The channel state information reportingdenotes reporting including at least one of CQI, PMI, RI, PTI and CRI.In addition, hereafter, if necessary, the channel state informationreporting may be discussed using CSI reporting or CQI reporting, andshould be construed as meaning including all of the channel stateinformation described above except for a particular situation.

Carrier aggregation (CA) technology is a technique for boosting a datatransmission rate for a UE through an additional carrier. Typical CAtechnology has not been optimized for the configuration of a SCell andan activation state for the SCell from latency perspective.

For example, a BS instructs a UE in an RRC connected state to perform ameasurement configuration on a frequency of a candidate cell, which maybe configured as a SCell on the UE, before configuring the CA. If the UEtransmits a measurement report to the BS according to a reportingconfiguration, the BS additionally configures a SCell on the UE based onthe received measurement report. When the SCell is configured on the UE,the SCell is configured to be in the deactivation state.

Thereafter, the BS may transmit user data by activating the SCellconsidering another measurement report, an amount oftransmitted/received data, and the like for the corresponding cell.

If the SCell is in the deactivation state, the UE does not i) transmitSRS on the SCell, ii) transmit on UL-SCH on the SCell, iii) transmit onRACH on the SCell, □) perform a channel quality indicator(CQI)/precoding matrix indicator (PMI)/rank indicator (RI)/proceduretransaction identifier (PTI)/CSI-RS resource indicator (CRI) report forthe SCell, □) monitor the PDCCH on the SCell, and □) perform PDCCHmonitoring for the SCell.

If the SCell enters the activation state, normal operations of the SCellare performed. For example, a SCell in the activation state may performoperations, such as, SRS transmission, CQI/PMI/RI/PTI/CRI reporting forthe SCell, PDCCH monitoring, PUCCH transmission, or the like.

A MAC control element (MAC CE) is used to transition a typical SCell tothe activation state. When receiving the MAC CE for activating a SCellin a subframe n, the UE shall be capable of applying SCell activationoperations up to n+24 or n+34 subframes. Related timing specificationsare as follows.

When a UE receives an activation command for a SCell in subframe n, thecorresponding actions in 3GPP TS 36.321 shall be applied no later thanthe minimum requirement defined in [36.133] and no earlier than subframen+8, except for the following:

-   -   the actions related to CSI reporting on a serving cell which is        active in subframe n+8    -   the actions related to the sCellDeactivationTimer associated        with the secondary cell

These two operations shall be applied in subframe n+8.

-   -   the actions related to CSI reporting on a serving cell which is        not active in subframe n+8

This operation shall be applied in the earliest subframe after n+8 inwhich the serving cell is active.

The minimum requirements defined in the relevant 3GPP TS36.133 are asfollows.

In the case of SCell activation latency requirement, upon receivingSCell activation command in subframe n, the UE shall be capable oftransmitting valid CSI report and applying actions related to theactivation command as specified for the SCell being activated no laterthan in subframe n+24 provided the following conditions are met for theSCell:

-   -   During the period equal to max (5 measCycleSCell, 5 DRX cycles)        before the reception of the SCell activation command:    -   the UE has sent a valid measurement report for the SCell being        activated and    -   the SCell being activated remains detectable according to the        cell identification conditions specified in section 8.3.3.2,    -   SCell being activated also remains detectable during the SCell        activation delay according to the cell identification conditions        specified in section 8.3.3.2.

Otherwise upon receiving the SCell activation command in subframe n, theUE shall be capable of transmitting valid CSI report and applyingactions related to the activation command for the SCell being activatedno later than in subframe n+34 provided the SCell can be successfullydetected on the first attempt.

Thus, a considerable delay occurs until the UE becomes able to transmitdata through a SCell after having received a MAC CE indicating SCellactivation. That is, about 24 to 34 ms is consumed for performingeffective data scheduling based on valid CQI reporting.

When a SCell in the deactivation state enters the activation state, a UEperforms RF retuning, initial CQI measuring and CQI reporting. A methodof reducing time for estimating and reporting initial valid CQI may beconsidered as one of methods for rapidly transitioning a SCell to theactivation state. This method can be realized by the UE's measuring orreporting periodically the CQI for a configured SCell. However, theperiodical measurement or report of the CQI causes a problem ofconsuming power. As another method, a new state may be defined forinterrupting or not performing one or more of operations in theactivation state, which cause power consumption. Using such a new state,the state of the SCell can be rapidly transited to the activation stateto transmit data in the activation state. In case of defining the newstate of the SCell, it may require to perform additional operation, suchas, transition between the new SCell state and the typical activationstate, and transition between the new SCell state and the typicaldeactivation state, and the like.

The present disclosure proposes such a new state as the dormant stateand operations of a UE and a BS for transiting SCell states inaccordance with at least one embodiment.

As described above, in the typical CA technology, a considerable delayoccurs until the UE becomes able to transmit user data through a celladditionally configured with carrier aggregation, after the UE in anidle state has transitioned into an RRC connected state and configuredthe carrier aggregation. In particular, a considerable delay occursuntil the UE becomes able to transmit data through a SCell after havingreceived a MAC CE indicating SCell activation. Such delay may beshortened by reducing time for estimating and/or reporting an initialvalid CQI. However, no specific method has been proposed for reducingthe time of estimating and reporting. Further, such a method may alsohave a problem of consuming power. As another method, a new state may bedefined for controlling a SCell to not perform or interrupt activationstate operations causing power consumption. Using such a new state, itis possible to rapidly transition a state of the SCell to the activationstate to transmit data in the activation state. However, no specificmethod for defining a new state and controlling SCell based on the newstate has not been proposed.

The present disclosure provides a method and an apparatus for reducingdelay occurring until the UE becomes able to transmit data through aSCell after having received a MAC CE indicating SCell activation. Inaddition, the present disclosure introduces a SCell state, the dormantstate, and a method for i) transitioning into the activation state totransmit data or ii) transitioning into the deactivation state.

Meanwhile, for better understanding, hereinafter, at least oneembodiment of the present disclosure will be described based on the LTEradio access technology. However, description or at least one embodimentdiscussed below may be applied to a fifth generation new radio (5G NR)or other radio access technologies as well as the LTE radio accesstechnology. Hereinafter, description on well-known techniques will beomitted. The omitted description or some information elements shallrefer to information elements specified in the RRC standard TS 36.331.In addition, with respect to operations of a UE, some operations includeoperations specified in the MAC standard TS 36.321. Even thoughdescription on operations of a UE related to the definitions ofcorresponding information elements is not included in this disclosure,the corresponding description may be included in the present disclosureor incorporated into claims.

FIG. 1 is a flowchart illustrating operations of a UE according to atleast one embodiment of the present disclosure.

Referring to FIG. 1, a UE controlling a state of a secondary cell(SCell) (e.g., SCell state) may perform operations for receiving SCellstate indication information from a BS through an RRC message or a MACCE (S100). The SCell state indication information may indicate the stateof the SCell.

For example, the UE may receive SCell state indication informationthrough higher layer signaling or a MAC CE. The higher layer signalingmay denote an RRC message. The higher layer signaling and the MAC CE maybe received depending on a situation such as whether the UE configures aSCell.

In one example, the SCell state indication information may be includedin an RRC connection reconfiguration message that the UE receives forconfiguring a SCell. For example, the SCell state indication informationreceived through the RRC message may include a 1 bit parameterindicating one of the activation state and the dormant state. Ifconfiguration information for configuring the SCell is contained in theRRC message, but a parameter for the SCell state indication informationis not contained in the configuration information, the UE may configurethe SCell to be in the deactivation state. Thereafter, the UE maycontrol a state of the SCell according to SCell state indicationinformation received through the MAC CE.

As another example, after having configured the SCell, the UE maydynamically receive state indication information for the SCell throughthe SCell state indication information by the MAC CE. For example, theMAC CE including the SCell state indication information may have aformat including a field for indicating a state for the SCell as theactivation state or the dormant state for each SCell index. As anotherexample, the MAC CE including the SCell state indication information maybe formed in a format including a field for indicating a state for theSCell as the activation state or the deactivation state for each SCellindex.

In other words, the MAC CE may be divided into i) a first MAC CEconfigured to indicate a state for each SCell index as the activationstate or the deactivation state and ii) a second MAC CE configured toindicate a state for each SCell index as the dormant state or theactivation state. In this case, the first MAC CE and the second MAC CEare identified by one or more MAC PDU subheaders having logical channelIDs (LCID) different from each other. For example, the first MAC CE maybe identified by a MAC PDU subheader having an activation ordeactivation LCID value. The second MAC CE may be identified by a MACPDU subheader having a hibernation LCID value. Thus, the first MAC CEand the second MAC CE are arbitrary terms for dividing the MAC CE, andnot limited thereto. That is, the first MAC CE may be described as anactivation/deactivation MAC CE, and the second MAC CE may be describedas a hibernation MAC CE.

Operations for receiving and processing messages according to eachsituation will be described in detail below with reference to thedrawings.

Meanwhile, when the SCell state indication information indicates thedormant state, the UE may perform controlling a state of the SCell intothe dormant state (S120).

For example, the UE checks whether SCell state indication information iscontained in the RRC message or the MAC CE and controls states of theSCell according to the SCell state indication information. In anexample, when the SCell state indication information indicates thedormant state, the UE may configure a state of the SCell to be in thedormant state, or cause the state of the SCell to transition into thedormant state.

For example, when an RRC message for configuring the SCell on the UE isreceived and SCell state indication information is contained in the RRCmessage, the UE may configure the SCell to be in a state indicated bythe SCell state indication information. That is, when configuring theSCell on the UE, the UE may configure the SCell to be in the activationstate or in the dormant state according to the SCell state indicationinformation (e.g., the UE may perform operations for changing a state ofthe SCell to the activation state or the dormant state). If the SCellstate indication information is not contained in the RRC message forconfiguring the SCell, the UE may configure the SCell to be in thedeactivation state (e.g., the UE may perform operations for changing thestate of the SCell to the deactivate state).

As another example, the UE may receive a MAC CE indicating a state forthe configured SCell. For example, a MAC CE including the SCell stateindication information may include a field for indicating a state forthe SCell as the activation state or the dormant state for each SCellindex.

Specifically, if a value of an index field for the SCell is set to avalue indicating the activation state and if a state for the SCellindicated by the index is the dormant state, the UE may performoperations for changing a state of the SCell into the activation state.

As another example, when a value of an index field of the SCell is setto a value indicating the activation state and when a state for theSCell is not the dormant state, the UE may ignore the index field value.That is, the current state of the SCell may be remained.

As another example, as described above, there may be two types of MACCEs: a first MAC CE and a second MAC CE. The first MAC CE is configuredto indicate a state for the SCell as the activation or deactivationstate, and the UE may control a state of the SCell according to thecorresponding indication information. The second MAC CE is configured toindicate a state for the SCell as the activation or dormant state, andthe UE may control a state of the SCell according to a value of an indexfield described above and the current state of the corresponding SCell.

In addition, it is necessary for the UE to assume receipt of all of thefirst MAC CE and the second MAC CE. In this case, the UE may determine astate of the corresponding SCell by combining values of SCell indexfields indicated by the two MAC CEs. For example, it is possible for theUE to determine whether SCell state indication information indicates thedormant state by combining values of index fields for the SCell includedin each of the first MAC CE and the second MAC CE.

Meanwhile, the UE may perform operations for transmitting channel stateinformation reporting for the SCell in the dormant state according to adormant state CQI report period parameter set separately from anactivation state CQI report period parameter (S130).

For example, if the SCell is in the dormant state, the UE may reportchannel state information for the SCell. Specifically, the UE may reportCQI/PMI/RI/PTI/CRI for the SCell in the dormant state. In this case, theUE does not transmit SRS on the SCell in the dormant state. In addition,the UE does not transmit UL-SCH and RACH on the SCell in the dormantstate. In addition, the UE does not monitor PDCCH on the SCell in thedormant state. The UE does not monitor the PDCCH for the SCell in thedormant state. The UE does not also transmit PUCCH on the SCell in thedormant state.

As described above, when a SCell is controlled to be in the dormantstate or transited into the dormant state, the UE reports channel stateinformation for the corresponding SCell to a BS, but does not performthe other operations in the same manner as the deactivation state. Thus,the dormant state is similar to the deactivation state in performingsome of operations in the activation state.

The UE may use a CQI report period parameter(s) for channel stateinformation reporting for the SCell in the dormant state. For example,the UE reports channel state information to a BS at a period set basedon the CQI report period parameter(s). In this case, the CQI reportperiod parameter(s) for transmitting channel state information for aSCell in the dormant state is distinguished from a CQI report periodparameter(s) for transmitting channel state information for a SCell inthe activation state. That is, the UE receives the activation state CQIreport period parameter(s) and the dormant state CQI report periodparameter(s), and periodically transmits channel state information byapplying one of the period parameters according to a state of the SCell.

In accordance with the above-described embodiments of the presentdisclosure, the UE may control a state of a SCell to the dormant state,the activation state, or the deactivation state. Since the UE transmitschannel state information for a SCell in the dormant state to a BS, theUE may reduce delay time when causing the SCell to transition into theactivation state to use the SCell.

Hereinafter, operations of the UE are described in more detail withreference to the accompanying drawings.

FIG. 2 is a diagram illustrating an RRC message including SCell stateindication information according to at least one embodiment of thepresent disclosure.

Referring to FIG. 2, the UE may receive an RRC connectionreconfiguration message including configuration information thatindicates a configuration of a SCell. In this case, SCell stateindication information may be contained in the SCell configurationinformation as its one parameter. For example, the SCell stateindication information may be composed of a 1 bit parameter forindicating a state for a SCell configured or to be configuredadditionally as one of the activation state and the dormant state.

Through this, the UE may set an initial state for a SCell to beconfigured by checking SCell state indication information (e.g.,sCellState-r15). The operations thereof will be described below withreference to FIG. 3.

FIG. 3 is a flowchart illustrating operations for controlling a state ofa SCell through an RRC message according to at least one embodiment ofthe present disclosure.

Referring to FIG. 3, a UE receives an RRC message for adding orconfiguring a SCell from a BS (S300). For example, the BS or thecorresponding network may instruct a configured SCell to be in or totransition into the dormant state. To do this, the network (BS) may usethe RRC message.

For example, the SCell may be controlled to be in the deactivation statewhen the SCell is added/configured or in an initial stage after ahandover has been performed. As another example, the UE may receive anRRC connection reconfiguration message containing SCell state indicationinformation indicating the activation state for the SCell from the BS,to enable the UE to transmit user data rapidly through the configuredSCell. In this case, the UE may set the corresponding SCell to be in theactivation state when the SCell is added/configured or in an initialstage after a handover has been performed. As further another example,the UE may receive an RRC connection reconfiguration message containinginformation indicating the dormant state for the SCell from the BS, toenable the configured SCell to transition into the SCell activationstate rapidly. In this case, the UE may configure the correspondingSCell to be in the dormant state when the SCell is added/configured orin an initial stage after a handover has been performed.

For the above operations, when the UE receives an RRC message, the UEdetermines whether the RRC message includes SCell state indicationinformation (S310).

For example, the SCell state indication information may be contained incommon SCell configuration information (e.g., commonSCellconfig) appliedto a specific group of SCells, as its one information element. Thus, theSCell state indication information may be applied to the specific SCellgroup. As another example, the SCell state indication information maycontained in SCell configuration information (e.g., SCellToAddMod)applied to individual SCells, as its one information element. Thus, theSCell state indication information may be applied to a specific SCell.

Meanwhile, the SCell state indication information may be made of 2 bitsand represent a value of one of the dormant state, the activation state,and the deactivation state for a corresponding SCell. If the SCell stateindication information is made of 2 bits, it is possible to use onevalue as a spare value. For example, the SCell state indicationinformation may be composed of SCellstate ENUMERATE {activate,deactivate, dormant, spare}.

As another example, the SCell state indication information may be madeof 1 bit and represent a value indicating one of the dormant state andthe activation state for a corresponding SCell. For example, the SCellstate indication information may include SCellstate ENUMERATE {activate,dormant} or SCellstate ENUMERATE {TRUE(activate), FALSE(dormant}. Inthis case, the corresponding information element (e.g. SCellstate) maybe set as an optional information element. Accordingly, when the SCellstate indication information is not contained in the SCell configurationinformation, the SCell may be controlled to be in the deactivation statewhen the SCell is added/configured or in an initial stage after ahandover has been performed, as in the typical system (S320).

When the SCell state indication information is contained, the UE maydetermine whether the SCell state indication information indicates theactivation state (S330). When the SCell state indication information isset to a value indicating the activation state, the UE controls thecorresponding SCell to be in the activation state (S340).

Meanwhile, when the SCell state indication information is not set to avalue indicating the activation state, that is, set to a valueindicating the dormant state, the UE controls the corresponding SCell tobe in the dormant state (S350).

For example, when an RRC message containing information indicating thedormant state for a SCell is received, the UE does not transmit SRS onthe SCell. In addition, the UE does not transmit information throughUL-SCH on the corresponding SCell. In addition, the UE does not transmitinformation through RACH on the corresponding SCell. In addition, the UEdoes not monitor PDCCH on the corresponding SCell. In addition, the UEdoes not transmit PUCCH on the corresponding SCell. If an SCelldeactivation timer (sCellDeactivationTimer) associated with thecorresponding SCell is in operation, the UE stops/interrupts the Scelldeactivation timer. In addition, the UE flushes all HARQ buffersassociated with the corresponding SCell. In addition, the UEstops/interrupts a SCell deactivation timer (sCellDeactivationTimer)associated with the corresponding SCell and flushes all HARQ buffersassociated with the corresponding SCell.

However, the UE may transmit channel state information for thecorresponding SCell in accordance with a period indicated by a periodicCQI reporting configuration (e.g., period information, CQI PUCCHresource information, CQI format indication information, or one or morepieces of parameter information capable of calculating periodinformation) in the dormant state. The channel state informationcontains CQI/PMI/RI/PTI/CRI.

Thus, when configuring a SCell, the UE may determine a state of theSCell configured or to be configured based on SCell state indicationinformation and control the states of the SCell.

Meanwhile, the UE may change a state of the configured SCell based on aMAC CE received from a BS.

FIG. 4 is a diagram illustrating a format of a MAC control element (MACCE) according to one embodiment of the present disclosure. FIG. 5 is adiagram illustrating a format of a MAC CE according to anotherembodiment of the present disclosure.

Referring to FIGS. 4 and 5, MAC control elements (MAC CE) may have aformat including fields for indicating a state for the SCell as theactivation state or the dormant state for each SCell index.

Each format includes a reserve bit (R) and bits (Ci) separated by anindex of each cell. For example up to 7 SCell indexes may be indicatedas shown in FIG. 4. As another example, up to 31 SCell indexes may beindicated as shown in FIG. 5. Specifically, the MAC CE having one octetis identified by a MAC PDU subheader. The MAC CE has a fixed size andincludes a single octet containing 7 C fields and one R field. The MACCE having four octets is identified by a MAC PDU subheader. The MAC CEhas a fixed size and includes four octets containing 31 C fields and oneR field.

The UE may check an index of the corresponding SCell, check a bit valueof the corresponding index, and then determine whether to transition astate of the SCell.

For example, if a value of an index field for the SCell is set to avalue indicating the activation state and if a state of the SCell is thedormant state, the UE may transition the state of the SCell to theactivation state.

As another example, when a value of an index field of the SCell is setto a value indicating the activation state and when a state of the SCellis not the dormant state, the UE may ignore the index field value andmaintain a state at the time of receiving the MAC CE.

FIG. 6 is a diagram illustrating a procedure of changing a state of aSCell according to a MAC CE including SCell state indication informationaccording to at least one embodiment of the present disclosure.

Referring to FIG. 6, a MAC CE having one octet is applied when a servingcell index (ServCellIndex) is not greater than 8. Otherwise, a MAC CEhaving 4 octets is applied. Each SCell is assigned with a SCell index(SCellIndex) i and “i” denotes an index of a corresponding Scell. Thatis, in a MAC CE, a Ci field indicates a state of a SCell having aSCellIndex i. Otherwise, the MAC entity shall ignore the Ci field.

As shown in FIG. 6, the fields C₁, C₃, and C₅ are exemplarilyillustrated as having a value 0 or 1. It shows that i) a SCell having aSCell index 1 (C₁) is in the deactivation state, ii) a SCell having aSCell index 3 (C3) is in the dormant state, and iii) a SCell having aSCell index 5 (C5) is in the activation state, at the time of receivingthe MAC CE.

The Ci field is set to 1 to indicate that a SCell having the SCellIndexi is required to transition to the dormant state. The Ci field is set to0 to indicate that a SCell having the SCellIndex i is required to beactivated. The R field is set to 0 as a reserved bit.

When receiving a MAC CE, the UE determines state transition using i) thecurrent state of a SCell having the corresponding SCell index and ii) anindication value indicated by the MAC CE.

For example, when a value of an index field of a SCell is set to a valueindicating the activation state (ex, “0”), and when a current state ofthe SCell is the dormant state, the UE may transition the state of theSCell to the activation state. That is, since C₃ is set to 0, the UEtransitions the SCell having SCell index 3 in the dormant state to theactivation state.

As another example, when a value of an index field of a SCell is set toa value indicating the activation state (ex, “0”) and when a currentstate of the SCell is not the dormant state, the UE ignores the indexfield value. That is, even though C1 is set to 0, since the SCell havingSCell index 1 is not in the dormant state, the UE remains thecorresponding SCell in the deactivation state.

As another example, when a value of an index field of a SCell is set toa value indicating the dormant state (ex, “1”), the UE transitions thestate of the SCell to the dormant state. That is, since C5 is set to 1,the UE transitions the SCell having SCell index 5 to the dormant state.

In this way, the UE controls a state for the SCell based on the MAC CEincluding information indicating as either the activation state or thedormant state.

As described, the MAC CE may be divided into i) a MAC CE includingfields indicating one of the activation state and the dormant state andii) a MAC CE including fields indicating one of the activation state andthe deactivation state.

FIG. 7 is a diagram illustrating examples of logical channel identifier(LCID) values according to at least one embodiment of the presentdisclosure.

Referring to FIG. 7, a MAC CE may be divided into i) a first MAC CE setto indicate a state for each SCell as one of the activation state andthe deactivation state and i) a second MAC CE set to indicate a statefor each SCell as one of the dormant state and the activation state. Thefirst MAC CE and the second MAC CE may be identified by MAC PDUsubheaders having logical channel IDs (LCIDs) different from each other.

For example, a MAC PDU subheader having an LCID value of 11000 or 11011may indicate a MAC CE for indicating a state of a SCell as theactivation or deactivation state. A MAC PDU subheader having an LCIDvalue of 10011 or 10100 may indicate a MAC CE for indicating a state ofa SCell as the activation or the dormant state. In this way, each of thefirst MAC CE and the second MAC CE is identified by MAC PDU subheadershaving LCIDs different from each other. Also, each of the first MAC CEand the second MAC CE may be identified by different LCID values fromeach other according to MAC CE octet(s).

As described above, a MAC CE may indicate two states of a SCell, withoutusing the octet value. For example, a MAC CE may indicate the activationstate or the deactivation state.

Such a MAC CE for indicating two states (e.g., the activation state orthe deactivation state) may have field formats shown in FIGS. 4 and 5according to the octet(s). In this case, as described above, the MAC CEis divided according to values of MAC PDU subheader. For example, theactivation/deactivation MAC CE having one octet is applied when aserving cell index (ServCellIndex) is not greater than 8. Otherwise, theactivation/deactivation MAC CE having four octets is applied. A SCell isassigned with a SCell index (C_(i)), where “i” denotes an index of acorresponding SCell. A Ci field indicates the activation/deactivationstate of a SCell having a SCellIndex i (C_(i)). Otherwise, the MACentity shall ignore the C_(i) field. The Ci field is set to 1 toindicate that a corresponding SCell is required to be activated. The Cifield is set to 0 to indicate that a corresponding SCell is required tobe deactivated. The R field is set to 0 as a reserved bit.

Therefore, it is required to assume that the UE receives both of i) aMAC CE indicating the activation state or the deactivation state and ii)a MAC CE indicating the activation state or the dormant state. When asingle MAC CE is received, the UE identifies it based on a subheader ofa MAC PDU including the MAC CE and determines whether to trigger statetransition according to the field value and a state of the correspondingSCell. However, when two MAC CEs are received, a rule is needed forconfirming state transition instruction for the SCell.

FIG. 8 is a diagram illustrating operations for determining a state of aSCell when a UE receives both of first and second MAC CEs according toat least one embodiment of the present disclosure.

When the UE receives both the first MAC CE and the second MAC CE, the UEdetermines a value indicated by SCell state indication information basedon the combination of index field values for the SCell included in eachof the first MAC CE and the second MAC CE.

Referring to FIG. 8, the hibernation MAC control element (CE) is asecond CE that indicates one of the activation state and the dormantstate, and the Activation/Deactivation MAC CE is a first CE thatindicates one of the activation state and the deactivation state.

The values of the individual SCell index fields in each MAC CE may beset to 0 or 1. In this case, a state of the corresponding SCell may betransitioned to the deactivation, activation or dormant state, dependingon the combination of a specific SCell index field value set in each MACCE, as shown in FIG. 8.

For example, when the field value for a specific SCell index of thesecond CE is 0, and the field value for the same specific SCell index ofthe first CE is 0, then the corresponding SCell shall be controlled tobe in the deactivation state. Likewise, when the field value of thesecond CE is 0 and the field value of the first CE is 1, thecorresponding SCell shall be caused to be in the activation state. Inaddition, when the field value of the second CE is 1 and the field valueof the first CE is 1, the corresponding SCell shall be caused to be inthe dormant state. A state where the field value of the second CE is 1and the field value of the first CE is 0 has been reserved and may beutilized in future.

Meanwhile, when it is determined that a state for a specific SCell isthe activation state, the UE's MAC entity does not transmit SRS on thecorresponding SCell.

The UE reports CQI/PMI/RI/PTI/CRI for the corresponding SCell inaccordance with a period indicated by a periodic CQI reportingconfiguration (e.g., period information, CQI PUCCH resource information,CQI format indication information, or one or more pieces of parameterinformation capable of calculating period information) in the dormantstate. In addition, the UE does not transmit information through UL-SCHon the corresponding SCell. In addition, the UE does not transmitinformation through RACH on the corresponding SCell. In addition, the UEdoes not monitor PDCCH on the corresponding SCell. In addition, the UEdoes not transmit PUCCH on the corresponding SCell.

If a SCell deactivation timer (sCellDeactivationTimer) associated withthe corresponding SCell is in operation, the UE stops/interrupts it. TheUE flushes all HARQ buffers associated with the corresponding SCell. Asanother example, the UE stops/interrupts the SCell deactivation timer(sCellDeactivationTimer) associated with the SCell when the SCelltransitions from the activation state to the dormant state. The UEflushes all HARQ buffers associated with the corresponding SCell.

FIG. 9 is a flowchart illustrating operations of a base stationaccording to at least one embodiment of the present disclosure.

Referring to FIG. 9, a BS controlling a state for a secondary cell(SCell) of a UE may perform operations transmitting SCell stateindication information indicating a state for the SCell through an RRCmessage or a MAC CE (S900).

For example, the BS may transmit the SCell state indication informationthrough higher layer signaling or a MAC CE. The higher layer signalingmay denote an RRC message. The higher layer signaling and the MAC CE maybe transmitted depending on a situation such as whether the UEconfigures a SCell.

For example, the SCell state indication information may be contained inan RRC connection reconfiguration message when the BS transmits the RRCconnection reconfiguration message for configuring a SCell of the UE.For example, the SCell state indication information transmitted throughthe RRC message may include 1 bit parameter indicating the activationstate or the dormant state. If configuration information for configuringthe SCell is contained in the RRC message, but a parameter for the SCellstate indication information is not contained in the configurationinformation, the UE may configure the SCell to be in the deactivationstate. Thereafter, the BS may control a state for the SCell according toSCell state indication information transmitted through the MAC CE.

As another example, after the UE has configured the SCell, the BS maydynamically transmit SCell state indication information through the MACCE. For example, the MAC CE including the SCell state indicationinformation may be configured in a format including a field forindicating a state for the SCell as the activation state or the dormantstate for each SCell index. As another example, the MAC CE including theSCell state indication information may have a format including a fieldindicating a state for the SCell as the activation state or thedeactivation state for each SCell index.

In other words, the MAC CE may be divided into a first MAC CE set toindicate a state for each SCell index as the activation state or thedeactivation state and a second MAC CE set to indicate a state for eachSCell index as the dormant state or the activation state. In this case,the first MAC CE and the second MAC CE are identified by MAC PDUsubheaders having logical channel IDs (LCID) different from each other.

When the SCell is controlled to be in the dormant state according to theSCell state indication information, the BS performs operations forreceiving channel state information reporting for the SCell in thedormant state according to a dormant state CQI report period parameterset separately from a activation state CQI report period parameter(S910).

For example, if the SCell of the UE is in the dormant state, the BS mayreceive channel state information for the SCell. Specifically, the BSmay receive CQI/PMI/RI/PTI/CRI for the SCell in the dormant state.However, as described above, the BS does not receive the SRS on theSCell in the dormant state. In addition, the BS does not receive UL-SCHon the SCell in the dormant state. In addition, the BS does not transmitPDCCH on the SCell in the dormant state. The BS does not transmit thePDCCH for the SCell in the dormant state. The BS does not also performan operation for receiving PUCCH on the SCell in the dormant state.

The BS may transmit a CQI report period parameter(s) for channel stateinformation reporting for the SCell in the dormant state. For example,the BS receives channel state information from the UE at a period setbased on the CQI report period parameter(s). In this case, the CQIreport period parameter(s) for transmitting channel state informationfor a SCell in the dormant state is distinguished from a CQI reportperiod parameter(s) for transmitting channel state information for aSCell in the activation state. That is, the BS transmits the activationstate CQI report period parameter(s) and the dormant state CQI reportperiod parameter(s) and periodically receives channel state informationby applying a specific period parameter according to a state of theSCell.

In addition, the BS may perform operations for performing operations ofthe UE described with reference to FIGS. 1 to 8.

As described above, according to the embodiments of the presentdisclosure, the UE may control a state of a SCell to the dormant state,the activation state, or the deactivation state depending on the controlof the BS. In addition, since the UE transmits channel state informationfor a SCell in the dormant state to a BS, the UE may reduce delay timewhen causing the SCell to transition into the activation state to usethe SCell.

Hereinafter, the above-described dormant state control method andcontrol timing will be described in more detail with variousembodiments.

Various embodiments for indicating a state of a SCell through a MAC CEwill be described.

A BS may transmit a MAC CE to a UE to indicate the dormant state for oneor more SCells.

Embodiment 1: A Method of Indicating the Dormant State Using a R Bit inthe MAC CE Field

For example, the BS may utilize a typical activation/deactivation MAC CE(or a typical activation/deactivation MAC CE format) to indicate thedormant state for a SCell configured on a UE. For example, theindication will be given as follows.

The R field may be set to 1 to indicate the dormant state that isdistinct from the activation state.

When the R field has been set to 1, the Ci field may be set to 1 toindicate that a SCell having a SCellIndex i shall be hibernated in thedormant state. As another embodiment, the Ci field may be set to 0 toindicate that the SCell having a SCellIndex i shall be hibernated. Inthis case, the Ci field may be set to 1 for indicating the remainingstates.

When the R field has been set to 1, the Ci field is set to 0 to indicatethat the SCell having a SCellIndex i shall be deactivated.

As another example, when the R field has been set to 1, the Ci field maybe set to 0 to indicate that the SCell having the SCellIndex i shall beactivated.

As further another example, regardless of the R field, the Ci field maybe set to 0 to indicate that the SCell with the SCellIndex i shall bedeactivated.

As still another example, LCID values may be 11011 in the case of theactivation/deactivation MAC CE having one octet, and the LCID value maybe 110000 in the case of the activation/deactivation MAC CE having fouroctets.

As another example, information for instructing operations, such ason/indicating/enabling/configuring may be transmitted to the UE throughan RRC reconfiguration message.

Embodiment 2: A Method of Indicating the Dormant State Using One (or aSpecific Bit) of the Ci Fields in the MAC CE Field

For example, the BS may use a typical activation/deactivation MAC CE (ora typical activation/deactivation MAC CE format) to indicate the dormantstate for a SCell configured on a UE.

As one example, one field or a bit in an activation/deactivation MAC CEmay be used to indicate the dormant state that is distinct from theactivation state. For example, the corresponding field or bit is set to1.

As another example, one specific Ci in the activation/deactivation MACCE may be used to indicate the dormant state that is distinct from theactivation state. For example, the corresponding field or bit is set to1 (or a dedicated value).

For example, a field or bit for indicating activation/deactivation maybe configured on the UE through an RRC connection reconfigurationmessage. For example, information for indicating/enabling/configuringthe operation may be configured on the UE through an RRC connectionreconfiguration message. As another example, a field or bit forindicating the dominant state may be previously configured, andinformation for indicating/enabling/configuring such an operation may beconfigured on the UE through an RRC connection reconfiguration message.For another example, the BS does not configure a SCell having a Scellindex or a servecell index of a corresponding field on the UE. As aresult, the corresponding index may be utilized as a field or bit forindicating the dormant state described above.

If the field or bit for indicating the dormant state is set to 1, theremaining fields (or Ci fields that are not used for indicating thedormant state) are set to 1 in order to indicate that the SCell havingthe SCellIndex i shall be hibernated in the dormant state. If the fieldor bit is set to 0 to indicate that the SCell with the SCellIndex ishall be hibernated, the field or bit is set to 1 to indicate theremaining states.

For example, when the field or bit for indicating the dormant state hasbeen set to 1, the remaining fields or the Ci fields that are not usedfor indicating the dormant state are set to 0 to indicate that the SCellhaving the SCellIndex i shall be deactivated.

As another example, when the field or bit for indicating the dormantstate has been set to 1, the remaining fields or the Ci fields that arenot used for indicating the dormant state are set to 0 to indicate thatthe SCell having the SCellIndex i shall be activated.

As further another example, regardless of the field or bit forindicating the dormant state, the remaining fields or the Ci fields thatare not used for indicating the dormant state may be set to 0 toindicate that the SCell having the SCellIndex i shall be deactivated.

As still another example, LCID values may be used with the same valuesas the typical activation/deactivation MAC CE (for example, in the caseof the activation/deactivation MAC CE of one octet, LCID value may be11011, and in the case of the activation/deactivation MAC CE of fouroctets, the LCID value may be 11000).

Embodiment 3: A Method of Indicating the Dormant State Using a ReservedLCID Value

As described above, for example, a new LCID distinct from the LCID ofthe typical activation/deactivation MAC CE may be assigned to indicatethe dormant state.

In one example, the BS may utilize the same format as the typicalactivation/deactivation MAC CE, but assign a new LCID distinct from theLCID of the typical activation/deactivation MAC CE. For example, theindication will be given as follows.

Here, a SCell is assigned with a SCell index (SCellIndex) i, where “i”denotes an index of the SCell. A Ci field indicates the dormant state ofa SCell having the SCellIndex i. Otherwise, the MAC entity shall ignorethe Ci field. For example, the Ci field is set to 1 to indicate that aSCell having the SCellIndex i is required to transition to the dormantstate. The Ci field is set to 0 to indicate that a SCell having theSCellIndex i is required to be deactivated.

As another example, the Ci field is set to 1 to indicate that a SCellhaving the SCellIndex i is required to transition to the dormant state.The Ci field is set to 0 to indicate that a SCell having the SCellIndexi is required to be activated.

As another example, the Ci field is set to 0 to indicate that a SCellhaving the SCellIndex i is required to transition to the dormant state.The Ci field is set to 1 to indicate that a SCell having the SCellIndexi is required to be activated.

The R field is set to 0 as a reserved bit.

Meanwhile, it is possible to i) define a dormant/activation MAC CE and adormant/deactivation MAC CE, ii) assign a new LCID distinct from theLCID of the typical activation/deactivation MAC CE, and therefore iii)indicate dormancy/activation and dormancy/deactivation, respectively.

In the case of the dormant/activation MAC CE, if a SCell is assignedwith a SCell index (SCellIndex) i, the corresponding Ci field indicatesthe dormant state of a SCell having the SCellIndex i. Otherwise, the MACentity shall ignore the Ci field. For example, the Ci field is set to 1to indicate that a SCell having the SCellIndex i is required totransition to the dormant state. The Ci field is set to 0 to indicatethat a SCell having the SCellIndex i is required to be activated.

In the case of the dormant/deactivation MAC CE, if a SCell is assignedwith a SCell index (SCellIndex) i, the corresponding Ci field indicatesthe dormant state of a SCell configured with the SCellIndex i.Otherwise, the MAC entity shall ignore the Ci field. For example, the Cifield is set to 1, to indicate that a SCell having the SCellIndex i isrequired to transition to the dormant state. The Ci field is set to 0 toindicate that a SCell having the SCellIndex i is required to bedeactivated.

As another example, the Ci field is set to 1 to indicate that a SCellhaving the SCellIndex i is required to transition to the dormant state.The Ci field is set to 0 to indicate that a SCell having the SCellIndexi is required to be in another state other than the dormant state. Ifthe corresponding MAC CE is intended to indicate a transition betweenthe dormant state and the activation state, a UE (MAC entity,hereinafter, the UE may be referred to as a MAC entity) transitions toor remains the dormant state when a SCell in the activation state (ordormant state) is instructed to be in the dormant state (set to “1”).When the cell in the dormant state (or activation state) is instructedto transit into the activation state (set to “0”), the UE transitions toor remains the activation state. When a cell in the deactivation stateis indicated by a corresponding MAC CE, the UE may ignore thecorresponding Ci field.

If the corresponding MAC CE is intended to indicate a transition betweenthe dormant state and the deactivation state, the UE transitions to orremains the dormant state when a SCell in the deactivation state (ordormant state) is instructed to be in the dormant state (set to “1”).When the cell in the dormant state (or deactivation state) is instructedto be in the deactivation state (set to “0”), the UE transitions to orremains the deactivation state. When a cell in the activation state isindicated by a corresponding MAC CE, the UE may ignore the correspondingCi field.

As another example, the MAC CE may be comprised of one MAC CE, and a 1bit field may be required to distinguish whether the corresponding MACCE is for indicating a transition between the dormant state and theactivation state, or a transition between the dormant state and thedeactivation state.

Embodiment 4: A Method of Indicating a Dormant State MAC CE Using OneLCID Field

FIG. 10 is a diagram illustrating a list of logical channel identifier(LCID) values for a DL-SCH according to an embodiment of the presentdisclosure.

As shown in FIG. 10, in the typical LTE technology, the LCID valueincludes 5 bits. Therefore, logical channels, MAC CEs, padding, and thelike are required to be divided into 32 or less. However, the number ofremaining spare bits is not large. Thus, it may be a waste i) if twodormant MAC CEs for both one octet and four octets are used for adormant MAC CE or ii) if a new LCID is defined for adormant/deactivation MAC CE or a dormant/activation MAC CE.

In order to not waste, it is possible to define a dormant MAC CE formatof one octet to four octets using one LCID, or it is possible to definea new MAC CE format for indicating activation/deactivation, using oneLCID. That is, it is possible to define a dormant MAC CE format ofvarying length or a MAC CE format for indicatingactivation/deactivation, through one MAC CE format.

FIG. 11 is a diagram illustrating a format of a MAC CE according toanother embodiment of the present disclosure.

Referring to FIG. 11, for example, a MAC CE format may include a length(Len) field to indicate whether a CSi field equal to or greater than aspecific number (for example, 6 bits or 7 bits) or a Cell State i (stateinformation of a SCell having a serving cell index/SCellindex i) isincluded. The length field may be referred to as variable lengthindication information or a MAC CE size field (bit). The length fieldmay be replaced by any term having the same meaning and may include onebit, two bits or three bits. The length (Len) field including one bitwill be described as a reference, but the embodiments of the presentdisclosure are not limited thereto.

If the length field/bit is set to 1, CSi fields may be included up to aspecific number (e.g., serving cell index/SCellindex 7 or 15 or 23). Ifthe length field/bit is set to 0, CSi fields may be included up to allSCell indexes (e.g., serving cell index/SCellindex 31).

For example, if the length field/bit is set to 1, CSi fields may beincluded up to serving cell index/SCellindex 7 or 15 or 23. If thelength field/bit is set to 0, CSi fields may be included up to servingcell index/SCellindex 31.

The Len field/bit including two bits will be described. The lengthfield/bit may have four values of 00, 01, 10 and 11. Through this, it ispossible to indicate each of the CSi fields up to the serving cellindex/SCellindex 7, the CSi fields up to the serving cellindex/SCellindex 15, the CSi fields up to the serving cellindex/SCellindex 23, and the CSi fields up to the serving cellindex/SCellindex 31. For example, if the length field is set to 00, theCSi fields may be included up to the serving cell index/SCellindex 7. Ifthe length field is set to 01, the CSi fields may be included up to theserving cell index/SCellindex 15. If the length field is set to 10, theCSi fields may be included up to the serving cell index/SCellindex 23.If the length field is set to 11, the CSi fields may be included up tothe serving cell index/SCellindex 31.

Hereinafter, the CSi field will be described.

For example, a state CSi field of a SCell having serving cellindex/SCellindex i may be composed of 1 bit field when only the dormantand activation states are defined or only the dormant and deactivationstates are defined.

As another example, a state CSi field of a SCell having serving cellindex/SCellindex i may be made of 2 bit field when the dormant,activation and deactivation states are defined. The dormant state,activation state, and deactivation state may be distinguished by threevalues of 00, 01, 10, and 11 that can be configured using 2 bits, andthe remaining value may be set as spare/reserved bits. When indicatedwith the remaining one value in the corresponding CSi field, a UE mayignore the CSi field.

Meanwhile, an extension field may be used instead of using the lengthfield/bit.

As another example of a varying length MAC CE, it may be possible todefined an extension field indicating a flag to indicate whether moreCSi fields are provided on a per one octet basis or on a per two octetbasis. For example, the extension field may be included in a bit(s) nextto the reserved bit if the extension field is used in the start bit ofeach octet, or in the last bit of each octet.

In one example, CSi fields included in at least one octet may beincluded when the extension field indicating a flag for indicatingwhether more CSi fields are provided per one octet is set to 1. Up toseven CSi fields may be included if the CSi field includes' bit. Up to 3CSi fields may be included if the CSi field is comprised of 2 bits. Ifthis extension field is set to 0, it indicates that one MAC SDU orpadding is to be started in the next byte.

In one example, CSi fields included in at least two octets may beincluded when the extension field indicating a flag for indicatingwhether more CSi fields are provided per two octets is set to 1. Up to15 CSi fields may be included if the CSi field is composed of 1 bit. Upto 7 CSi fields may be included if the CSi field is made of 2 bits. Ifthis extension field is set to 0, it indicates that one MAC SDU orpadding is to be started in the next byte.

As another example, the subheader of a corresponding MAC CE may includeinformation for distinguishing a MAC CE for 1 octet and a MAC CE for 4octets. As another example, the subheader of a corresponding MAC CE mayinclude information for indicating the number of octets of the MAC CEthrough a field representing the number of octets or a length field.

It is possible to include information to indicate whether the remainingstate(s) is the activation state or the deactivation state according tothe R field, using the R field (or a specific field) on the MAC CEindicating the dormant state. For example, in the case of the dormantMAC CE, if a SCell configured is assigned with a SCell index(SCellIndex) i, the Ci field indicates the dormant state of a SCellhaving the SCellIndex i. Otherwise, the MAC entity shall ignore the Cifield. In one example, the Ci field is set to 1 to indicate that a SCellhaving the SCellIndex i is required to transition to the dormant state.When the R field is set to 0, the Ci field is set to 0 to indicate thatthe SCell with the SCellIndex i shall be deactivated. When the R fieldis set to 1, the Ci field is set to 0 to indicate that the SCell withthe SCellIndex i shall be activated. As another example, the Ci field isset to 1 to indicate that a SCell having the SCellIndex i is required totransition to the dormant state. When the R field is set to 0, the Cifield is set to 0 to indicate that the SCell with the SCellIndex i shallbe activated. When the R field is set to 1, the Ci field is set to 0 toindicate that the SCell with the SCellIndex i shall be deactivated. Forconvenience of description, although the R field has been described, itis also included in the scope of the present disclosure to designate andprocess arbitrary fields included in the MAC CE as described above.

Embodiment 5: A Way of Distinguishing MAC CEs Indicating the DormantState by Increasing the LCID Field Value to 6 Bits

FIG. 12 is a diagram illustrating a format of a MAC PDU including a MACheader and a MAC payload according to at least one embodiment of thepresent disclosure. FIG. 13 is a diagram illustrating a format of a MACsubheader.

Referring to FIG. 12, the typical LTE LCID field value of 5 bits may beincreased to 6 bits. In this case, the MAC subheader value is increasedto 6 bits, which seriously affects byte the aligned MAC subheader.

Specifically, referring to the MAC subheader format of FIG. 13, if theLCID increases from 5 bits to 6 bits, one more byte may be required.That is, the LCID is increased by one bit, but the MAC subheader isrequired to increase by one byte. As one example to prevent suchinefficiency, the R field included in the MAC subheader format may becombined with the LCID field to configure a LCID with a 6-bit LCID.

As another example, one bit on an arbitrary field included in the MACsubheader format may be combined with bits in the LCID field toconfigure a LCID with a 6-bit LCID.

As described above, embodiments have been described in which the BSindicates the dormant state for a SCell to the UE, through variousformats and utilization of the MAC CE. Embodiments described above maybe taken individually or in combination partly or entirely.

Hereinafter, operations of a UE will be described with reference totiming when the UE receives a MAC CE indicating the dormant state.

FIG. 14 is a diagram illustrating timing for receiving each ofactivation state indication information, dormant state indicationinformation, and deactivation state indication information for a SCellaccording to at least one embodiment of the present disclosure.

Referring to FIG. 14, description will be given for operations performedby a UE in terms of timing when a MAC CE including SCell stateindication information indicating each state is received will bedescribed.

In one example, when the UE receives a MAC CE indicating the dormantstate, the UE may perform CSI reporting at time point n+8 (or after thetime point n+8 or at a first period after the time point n+8) from timepoint n when a corresponding MAC CE message is received. The UE maystart or restart an associated timer.

As another example, when the UE receives a MAC CE indicating the dormantstate, the UE may perform periodic CSI reporting after time point n+8from time point n when a corresponding MAC CE message is received andbefore time point n+24 or n+34. The UE may start or restart anassociated timer.

As another example, when the UE receives a MAC CE indicating the dormantstate, the UE may perform periodic CSI reporting before time point n+24or n+34 from time point n when a corresponding MAC CE message isreceived. The UE may start or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting at time point n+8 fromi) the time point when the RRC connection reconfiguration message isreceived, ii) the time point when the RRC connection reconfigurationmessage is processed and decoded, or iii) the time point when an RRCconnection reconfiguration completion message is transmitted. The UE maystart or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting before time point n+24or n+34 from the time point when the RRC connection reconfigurationmessage is received. The UE may start or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting at time point n+8 fromthe time point when the decoding of the RRC connection reconfigurationmessage is completed. The UE may start or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting at the time point whenan RRC connection reconfiguration completion message is transmitted. TheUE may start or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting at the time point whenan offset parameter(s) indicated by a BS (being included in the RRCconnection reconfiguration message) is applied based on a time pointwhen an RRC connection reconfiguration completion message istransmitted. The UE may start or restart an associated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform CSI reporting at the first period of periodicCSI reporting from the time point when an RRC connection reconfigurationcompletion message is transmitted. The UE may start or restart anassociated timer.

As another example, when the UE receives an RRC connectionreconfiguration message including information indicating the dormantstate, the UE may perform periodic CSI reporting at an earliest timepoint from the time point when an RRC connection reconfigurationcompletion message is transmitted. The UE may start or restart anassociated timer. In this case, the earliest time point shall be withintime point n+24 or n+34 from the time point when the RRC reconnectionmessage is received or when the decoding of the RRC connectionreconfiguration message is completed.

As described above, when the UE receives the SCell state indicationinformation indicating the dormant state, the UE transmits the channelstate information to the BS at a specific time.

Hereinafter, a method of a UE for rapidly transmitting data through aSCell by reducing time for estimating and reporting an initial validCQI, after having received information indicating the activation statefor a SCell through the activation/deactivation MAC CE will bedescribed.

SCell activation delay is caused by CQI computation delay (4˜6 ms), timefor waiting valid resources for CSI measurement report, time for RFre-tuning, and the like.

A UE may perform CSI reporting when it reaches n+8 after the time (n)when an activation command is received. Therefore, if the UE is allowedto inform the network that it is ready to use an activated SCell bytransmitting an UL signal in a short period of time, it is possible toreduce delay in activating the SCell to transmit data.

When an UL resource is allowed/assigned in a corresponding SCell, the UEtransmits CQI reporting to the BS in a short period of time.

The BS may enable a CQI reporting resource of a short period to beavailable to the UE when an SCell activation command is received.

To do this, the UE may be assigned with a specific CQI resource on theSCell. As another example, the UE may be allocated with a specific CQIresource for the corresponding SCell on the PCell. As another example,the UE may be allocated with a specific CQI resource for thecorresponding SCell on a PUCCH SCell. The BS may provide information ona specific CQI resource, which is included in the RRC connectionreconfiguration message, to the UE.

When the UE receives a SCell activation command, the UE transmits a CQIreport (for convenience of description, CQI reporting is used and alsoincludes a channel quality indicator (CQI) report, a precoding matrixindicator (PMI) report, a rank indicator (RI) report, a proceduretransaction identifier (PTI) report, a CSI-RS Resource Indicator (CRI)report) through the PCell or another SCell or PUCCH SCell, to indicatethat the corresponding SCell has been activated. Alternatively, the UEmay report through the SCell in the activation state.

To avoid a load on a PUCCH resource, the short period of the CQIreporting resource shall be available only when a SCell activationcommand is received. However, if the UE transmits CQI reporting throughthe PUCCH, load may be caused because the PUCCH resource is continuouslyused when the SCell activation command is received.

To solve this problem, it is necessary for the UE to performswitching/fallback/conversion in a normal period (or a period set longerthan a short period for indicating/informing SCell activation to theBS).

For example, when a UE receives a SCell activation command (if a MAC CEindicating SCell activation is received), i) a CQI configuration havinga short CQI reporting period (for valid CQI reporting) and ii) a CQIconfiguration having a CQI reporting period of a normal period (or aperiod longer than a short period for indicating/informing the SCellactivation to the BS) in the activation state may be performed at the UEthrough the RRC connection reconfiguration message. That is, asdescribed above, the BS may configure a CQI report period parameter fortransmitting channel state information in the activation state and a CQIreport period parameter for transmitting channel state information inthe deactivation state for the UE.

As another example, when the UE receives a MAC CE indicating SCellactivation, a CQI configuration having a short CQI reporting period (forvalid CQI reporting) may include one or more pieces of information forindicating i) a CQI reporting start offset for corresponding CQIreporting, ii) a corresponding CQI reporting period (e.g., 1 ms), andiii) number of repetitions of corresponding CQI reporting. The CQIreporting period may be pre-configured with a specific value for a UEcapable of a corresponding function. For example, if the CQI reportingis transmitted as many times as the number of repetitions of the CQIreporting, the UE may perform switching/fallback/conversion in a CQIreporting period of a normal period (or a period longer than a shortperiod for indicating/informing SCell activation to the BS) in theactivation state.

As another example, when receiving a MAC CE indicating SCell activation,the UE reports the CQI through a short CQI reporting period. When the UEreceives resource allocation (ex, DL allocation, UL grant) for acorresponding SCell form the BS, the UE may performswitching/fallback/conversion in a CQI reporting period of a normalperiod in the activation state.

As another example, when the UE receives a MAC CE indicating SCellactivation, the UE reports the CQI through a short CQI reporting period.When a specific subframe is exceeded in a subframe(s) that has receiveda MAC CE, the UE may perform switching/fallback/conversion in a CQIreporting period of a normal period in the activation state. Afterhaving received the SCell activation indication, the correspondingspecific subframe may be 24 or 34 subframes in which SCell activationoperation is applied. A BE configures the corresponding subframe for aUE or may pre-configure the corresponding subframe with a specific valuefor a UE capable of a corresponding function.

As another example, when the UE receives a MAC CE indicating SCellactivation, the UE reports the CQI through a short CQI reporting period.The UE may perform switching/fallback/conversion in a CQI reportingperiod of a normal period in the activation state at a timecorresponding to the minimum value/time of the operation/method/time.

As described above, the UE configures a period parameter for CQIreporting in the dormant state separated from a period parameter for CQIreporting in the activation state and may transmit a CQI reportaccording to the corresponding configuration and a state of the SCell.In addition, the CQI reporting period may be changed according tomethods described above.

According to the above-described embodiments of the present disclosure,the UE may rapidly activate the SCell to transmit user data. Thus, theoffloading effect may be improved by reducing delay for activating aSCell from the dormant state and allowing data through the SCell to betransmitted rapidly.

Hereinafter, a UE and a BS capable of performing a part or all ofembodiments described above will be discussed again with reference tothe drawings.

FIG. 15 is a block diagram illustrating a UE according to at least oneembodiment of the present disclosure.

Referring to FIG. 15, a UE 1500 controlling states of a SCell mayinclude a receiver 1530 configured to receive SCell state indicationinformation indicating a state for the SCell from a BS through an RRCmessage or a MAC control element, a controller 1510 configured to causea state of the SCell to transition into the dormant state when the SCellstate indication information indicates the dormant state, and atransmitter 1520 configured to transmit channel state informationreporting for the SCell in the dormant state according to an dormantstate CQI report period parameter set separately from an activationstate CQI report period parameter.

For example, the receiver 1530 may receive SCell state indicationinformation through higher layer signaling or a MAC CE. The higher layersignaling may denote an RRC message. The higher layer signaling and theMAC CE may be received depending on a situation such as whether the UEconfigures a SCell.

In one example, the SCell state indication information may be containedin an RRC connection reconfiguration message that the receiver 1530receives for configuring a SCell. For example, the SCell stateindication information received through the RRC message may be composedof 1 bit parameter indicating the activation state or the dormant state.If configuration information for configuring the SCell is contained inthe RRC message, but a parameter for the SCell state indicationinformation is not contained in the configuration information, thecontroller 1510 may configure the SCell to be in the deactivation state.Thereafter, the controller 1510 may control a state of the SCellaccording to SCell state indication information received through the MACCE.

As another example, after having configured the SCell, the receiver 1530may dynamically receive state indication information of the SCellthrough the SCell state indication information by the MAC CE. Forexample, the MAC CE including the SCell state indication information mayhave a format including a field for indicating a state for the SCell asthe activation state or the dormant state for each SCell index. Asanother example, the MAC CE including the SCell state indicationinformation may have a format including a field for indicating a statefor the SCell as the activation state or the deactivation state for eachSCell index.

In other words, the MAC CE may be divided into a first MAC CE set toindicate a state for each SCell index as the activation state or thedeactivation state, and a second MAC CE set to indicate a state for eachSCell index as the dormant state or the activation state. In this case,the first MAC CE and the second MAC CE are identified by MAC PDUsubheaders having logical channel IDs (LCID) different from each other.

For example, the controller 1510 checks whether SCell state indicationinformation is contained in the RRC message or the MAC CE and controls astate of the SCell according to the SCell state indication information.In an example, when the SCell state indication information indicates thedormant state, the controller 1510 may configure a state of the SCell tobe in the dormant state or cause the state of the SCell to transitioninto the dormant state.

In an example, when an RRC message for configuring the SCell on the UEis received and SCell state indication information is contained in theRRC message, the controller 1510 may configure the SCell to be in astate indicated by the SCell state indication information. That is, whenconfiguring the SCell on the UE, the controller 1510 may configure theSCell to be in the activation state or in the dormant state according tothe SCell state indication information. If SCell state indicationinformation is not contained in the RRC message for configuring theSCell, the controller 1510 may configure the SCell to be in thedeactivation state.

As another example, the receiver 1530 may receive a MAC CE indicating astate for the configured SCell. For example, the MAC CE including theSCell state indication information may include a field for indicating astate for the SCell as the activation state or the dormant state foreach SCell index.

Specifically, if a value of an index field for the SCell is set to avalue indicating the activation state, and if a state for the SCellindicated by the index is the dormant state, the controller 1510 maychange a state of the SCell to transition into the activation state.

As another example, when a value of an index field of the SCell is setto a value indicating the activation state, and when a state for theSCell is not the dormant state, the controller 1510 may ignore the indexfield value. That is, the current state of the SCell may be remained.

As another example, as described above, there may be two types of MACCEs: a first MAC CE and a second MAC CE. The first MAC CE indicates astate for the SCell as the activation or deactivation state, and the UEmay control a state of the SCell according to the correspondingindication information. The second MAC CE indicates a state for theSCell as the activation or dormant state, and the UE may control a stateof the SCell according to a value of an index field described above andthe current state of the corresponding SCell.

In addition, when both the first MAC CE and the second MAC CE arereceived, the controller 1510 may determine a state of the correspondingSCell by combining the values of the SCell index fields indicated by thetwo MAC CEs. For example, it is possible for the UE to determine whetherSCell state indication information indicates the dormant state bycombining values of index fields for the SCell included in each of thefirst MAC CE and the second MAC CE.

For example, if the SCell is in the dormant state, the transmitter 1520may report channel state information for the SCell. Specifically, thetransmitter 1520 may report CQI/PMI/RI/PTI/CRI for the SCell in thedormant state. In this case, the controller 1510 does not transmit SRSon the SCell in the dormant state. In addition, the transmitter 1520does not transmit UL-SCH and RACH on the SCell in the dormant state. Inaddition, the controller 1510 does not monitor PDCCH on the SCell in thedormant state. The UE does not monitor the PDCCH for the SCell in thedormant state. The transmitter 1520 does not also transmit PUCCH on theSCell in the dormant state.

The transmitter 1520 may use a CQI report period parameter(s) forchannel state information reporting for the SCell in the dormant state.For example, the transmitter 1520 reports channel state information to aBS at a period set based on the CQI report period parameter(s). In thiscase, the CQI report period parameter(s) for transmitting channel stateinformation for a SCell in the dormant state is distinguished from a CQIreport period parameter(s) for transmitting channel state informationfor a SCell in the activation state. That is, the receiver 1530 receivesthe activation state CQI report period parameter(s) and the dormantstate CQI report period parameter(s), and the transmitter 1520periodically transmits channel state information by applying one of theperiod parameters according to a state of the SCell.

In addition, the controller 1510 controls the overall operation of theUE 1500 to control the dormant state control and the channel stateinformation transmission operation for the SCell in a CA situationrequired for performing the embodiments.

The transmitter 1520 and the receiver 1530 are used to transmit, to theBS and receive from the BS, signals, messages, and data necessary forperforming embodiments of the present disclosure.

FIG. 16 is a block diagram illustrating a BS according to at least oneembodiment of the present disclosure.

Referring to FIG. 16, a BS 1600 controlling states of a SCell of a UEmay include a transmitter 1620 configured to transmit secondary cell(SCell) state indication information indicating a state for the SCell toa UE through an RRC message or a MAC control element, and when the SCellenters the dormant state according to the SCell state indicationinformation, a receiver 1630 configured to receive channel stateinformation reporting for the SCell in the dormant state according to andormant state CQI report period parameter set separately from anactivation state CQI report period parameter.

For example, the transmitter 1620 may transmit SCell state indicationinformation through higher layer signaling or a MAC CE. The higher layersignaling may denote an RRC message. The higher layer signaling and theMAC CE may be transmitted depending on a situation such as whether theUE configures a SCell.

For example, the SCell state indication information may be contained inan RRC connection reconfiguration message that the transmitter 1620transmits for configuring a SCell. For example, the SCell stateindication information transmitted through the RRC message may include 1bit parameter indicating the activation state or the dormant state. Ifconfiguration information for configuring the SCell is contained in theRRC message, but a parameter for the SCell state indication informationis not contained in the configuration information, the UE may configurethe SCell to be in the deactivation state. Thereafter, the BS 1600 maycontrol a state of the SCell according to SCell state indicationinformation transmitted through the MAC CE.

As another example, after the UE has configured the SCell, thetransmitter 1620 may dynamically transmit SCell state indicationinformation through the MAC CE. For example, the MAC CE including theSCell state indication information may have a format including a fieldfor indicating a state for the SCell as the activation state or thedormant state for each SCell index. As another example, the MAC CEincluding the SCell state indication information may have a formatincluding a field for indicating a state for the SCell as the activationstate or the deactivation state for each SCell index.

In other words, the MAC CE may be divided into a first MAC CE set toindicate a state for each SCell index as the activation state or thedeactivation state, and a second MAC CE set to indicate a state for eachSCell index as the dormant state or the activation state. In this case,the first MAC CE and the second MAC CE are identified by MAC PDUsubheaders having logical channel IDs (LCID) different from each other.

Meanwhile, if the SCell of the UE is in the dormant state, the receiver1530 may receive channel state information for the SCell. Specifically,the receiver 1530 may receiver CQI/PMI/RI/PTI/CRI for the SCell in thedormant state. However, as described above, the receiver 1530 does notreceive the SRS on SCell in the dormant state. In addition, the receiver1530 does not receive UL-SCH and RACH on the SCell in the dormant state.In addition, the transmitter 1520 does not transmit PDCCH on the SCellin the dormant state. The transmitter does not transmit the PDCCH forthe SCell in the dormant state. The controller 1510 does not alsoperform an operation for receiving PUCCH on the SCell in the dormantstate.

The transmitter 1520 may transmit a CQI report period parameter(s) forchannel state information reporting for the SCell in the dormant state.For example, the receiver 1530 receivers channel state information fromthe UE at a period set based on the CQI report period parameter(s). Inthis case, the CQI report period parameter(s) for transmitting channelstate information for a SCell in the dormant state is distinguished froma CQI report period parameter(s) for transmitting channel stateinformation for a SCell in the activation state. That is, thetransmitter 1520 transmits the activation state CQI report periodparameter(s) and the dormant state CQI report period parameter(s), andthe receiver 1530 periodically receivers channel state information byapplying one of the period parameters according to a state of the SCell.

In addition, the controller 1610 controls the overall operation of theBS 1600 to control the dormant state control and the channel stateinformation transmission operation for the SCell in a CA situationrequired for performing the embodiments.

The transmitter 1620 and the receiver 1630 are used to transmit, to theUE and receive from the UE, signals, messages, and data necessary forperforming embodiments of the present disclosure.

The embodiments described above may be supported by the standarddocuments disclosed in at least one of the wireless access systems IEEE802, 3GPP and 3GPP2. That is, the steps, configurations, and parts notdescribed in the present embodiments for clarifying the technical ideamay be supported by standard documents described above. In addition, allterms disclosed herein may be described by the standard documentsdescribed above.

The embodiments described above may be implemented by various means. Forexample, the embodiments of the present disclosure may be implemented byhardware, firmware, software, or a combination thereof.

In the case of hardware implementation, the method according toembodiments may be implemented by one or more of application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs)(Field Programmable Gate Arrays), a processor, a controller, amicrocontroller, a microprocessor, or the like.

In the case of an implementation by firmware or software, the methodaccording to the embodiments may be implemented in the form of anapparatus, a procedure, or a function for performing the functions oroperations described above. The software code may be stored in a memoryunit and driven by the processor. The memory may be located inside oroutside the processor, and may exchange data with the processor byvarious well-known means.

The terms “system”, “processor”, “controller”, “component”, “module”,“interface”, “model”, “unit”, and the like, described above maygenerally refer to computer-related entity hardware, a combination ofhardware and software, software, or software in execution. For example,components described above may be, but are not limited to, a processdriven by a processor, a processor, a controller, a control processor,an entity, an execution thread, a program and/or a computer. Forexample, an application running on a controller, controller or processorcan be a component. One or more components can be included within aprocess and/or thread of execution, and a component can be placed on onesystem or be disposed on more than one system.

The features, structures, configurations, and effects described in thepresent disclosure are included in at least one embodiment but are notnecessarily limited to a particular embodiment. A person skilled in theart can apply the features, structures, configurations, and effectsillustrated in the particular embodiment embodiments to another one ormore additional embodiment embodiments by combining or modifying suchfeatures, structures, configurations, and effects. It should beunderstood that all such combinations and modifications are includedwithin the scope of the present disclosure. Accordingly, the embodimentsof the present disclosure are intended to be illustrative rather thanlimiting, and the scope of the present invention is not limited by theseembodiments. The scope of protection of the present disclosure is to beconstrued according to the claims, and all technical ideas within thescope of the claims should be interpreted as being included in the scopeof the present invention.

What is claimed is:
 1. A method of controlling states of a secondarycell by a user equipment, the method comprising: receiving secondarycell (SCell) state indication information indicating a state for theSCell from a base station through an radio resource control (RRC)message or a medium access control (MAC) control element; causing astate of the SCell to transition into a dormant state when the SCellstate indication information indicates the dormant state; andtransmitting channel state information reporting for the SCell in thedormant state according to a dormant state channel quality indicator(CQI) report period parameter set separately from an activation stateCQI report period parameter.
 2. The method according to claim 1, whereinthe SCell state indication information received through the RRC messageincludes one bit parameter indicating one of an activation state and thedormant state.
 3. The method according to claim 2, further comprising,when the RRC message excludes the SCell state indication information,configuring the SCell to be in a deactivation state and changing thestate of the SCell to the dormant state according to the MAC controlelement.
 4. The method according to claim 1, wherein the MAC controlelement including the SCell state indication information has a formatincluding a field for indicating the state of the SCell as one of theactivation state and the dormant state for each SCell index.
 5. Themethod according to claim 4, further comprising, when a value of anindex field for the SCell is set to a value indicating the activationstate and the state of the SCell is the dormant state, transitioning thestate of the SCell to the activation state.
 6. The method according toclaim 4, further comprising, when a value of an index field for theSCell is set to a value indicating the activation state and the state ofthe SCell is not the dormant state, ignoring the value of the indexfield.
 7. The method according to claim 1, wherein the MAC controlelement is divided into i) a first MAC control element indicating astate for each SCell index as one of the activation state and thedeactivation state and ii) a second MAC control element indicating astate for each SCell index as one of the dormant state and theactivation state, wherein the first MAC control element and the secondMAC control element are identified by MAC protocol data unit (PDU)subheaders having logical channel identifiers (IDs) different from eachother.
 8. The method according to claim 7, further comprising, when boththe first MAC control element and the second MAC control element arereceived, determining whether the SCell state indication informationindicates the dormant state by combining values of index fields for theSCell included in each of the first MAC control element and the secondMAC control element.
 9. A method of controlling states of a secondarycell by a base station, the method comprising: transmitting secondarycell (SCell) state indication information indicating a state for theSCell to a user equipment through an radio resource control (RRC)message or a medium access control (MAC) control element; and when theSCell is configured to be in a dormant state according to the SCellstate indication information, receiving channel state informationreporting for the SCell in the dormant state according to a dormantstate CQI report period parameter set separately from a activation stateCQI report period parameter.
 10. The method according to claim 9,wherein the RRC message contains SCell configuration information forconfiguring the SCell on the user equipment, wherein the SCell stateindication information includes one bit parameter indicating anactivation state or the dormant state.
 11. The method according to claim9, wherein the MAC control element includes a format including a fieldfor indicating a state of the SCell as one of the activation state andthe dormant state for each SCell index.
 12. The method according toclaim 9, wherein the MAC control element is divided into a first MACcontrol element indicating a state for each SCell index as one of theactivation state and the deactivation state and a second MAC controlelement indicating a state for each SCell index as one of the dormantstate and the activation state, wherein the first MAC control elementand the second MAC control element are identified by MAC protocol dataunit (PDU) subheaders having logical channel identifiers (IDs) differentfrom each other.
 13. A user equipment controlling states of a secondarycell, the user equipment comprising: a receiver configured to receivesecondary cell (SCell) state indication information indicating a statefor the SCell from a base station through an radio resource control(RRC) message or a medium access control (MAC) control element; acontroller configured to cause a state of the SCell to transition into adormant state when the SCell state indication information indicates thedormant state; and a transmitter configured to transmit channel stateinformation reporting for the SCell in the dormant state according to adormant state channel quality indicator (CQI) report period parameterset separately from an activation state CQI report period parameter. 14.The user equipment according to claim 13, wherein the SCell stateindication information received through the RRC message includes aone-bit parameter indicating one of an activation state and the dormantstate.
 15. The user equipment according to claim 14, wherein when theRRC message excludes the SCell state indication information, thecontroller configures the SCell to be in a deactivation state andchanges the state of the SCell to the dormant state according to the MACcontrol element.
 16. The user equipment according to claim 13, whereinthe MAC control element including the SCell state indication informationhas a format including a field for indicating the state of the SCell asone of the activation state and the dormant state for each SCell index.17. The user equipment according to claim 16, wherein when a value of anindex field for the SCell is set to a value indicating the activationstate, and the state of the SCell is the dormant state, the controlleris configured to transition the state of the SCell to the activationstate.
 18. The user equipment according to claim 16, wherein when avalue of an index field for the SCell is set to a value indicating theactivation state, and the state of the SCell is not the dormant state,the controller is configured to ignore the value of the index field. 19.The user equipment according to claim 13, wherein the MAC controlelement is divided into a first MAC control element indicating a statefor each SCell index as one of the activation state and the deactivationstate and a second MAC control element indicating a state for each SCellindex as one of the dormant state and the activation state, wherein thefirst MAC control element and the second MAC control element areidentified by MAC protocol data unit (PDU) subheaders having logicalchannel identifiers (IDs) different from each other.
 20. The userequipment according to claim 19, wherein when both the first MAC controlelement and the second MAC control element are received, the controlleris configured to determine whether the SCell state indicationinformation indicates the dormant state by combining values of indexfields for the SCell included in each of the first MAC control elementand the second MAC control element.